Because he was such a good cook, the queen insisted that he cook her food, and take the title king of chefs and he's proud of it.
10 seconds sound clip from the Of Cooks And Kung Fu (1979) movie soundboard.
You can hear this line at 00:38:15 in the Blu-ray version of the movie.
Quote context
[...]
- Oh, the best food, but that's expensive.
- I don't care. Money's no object.
- In that case, how about food fit for an emperor?
- That sounds alright. Oh, yeah, but we'll need an emperors cook.
- Don't you worry cause I know every cook in the country. Even those in foreign countries.
- 10 miles from here at Shin Po bridge, there lives the king of chefs.
- This man was once a head chef at the emperors palace.
- That's quite a story. How come you know all the details?
[...]